what wrongs on the following sentence (passive voice)

1.你的手機已被偷了，應是已發生的事情，所以應用過去式，其實你都知道的，所以你也用了 could 字，so I COULD not contact you.

2. 第二句也有点問題，１是用了現在式的 is invent(應加ed 在後，passive voice)而不是過去式的 was; 2是火藥是由中國發明的，不是在中國發明，所以應該是 by China 而不是 in China. 因用了 by China, 不應用 where，　因不明你原來的意思，不能給你正確的答案．

3. 第三句也有問題，你不是說 the door is always leave open 嗎?　即是要常開了，　但你又說 It should (應加 be 在 should 之後, passive voice) shut, 那應該度門是應常開還是應常關呢?

1. My mobile has been stole, so i could not contact you

2. Gunpowder is invented in China which is used for fireworks.

3, The door is always left open. It should be shut.

1. My mobile was stolen, so I could not contact you.

2. Gunpowder was invented in China, where it is used for fireworks.

3. The door was always left open. It should be shut.

例如直接句的話是 Someone stole my mobile, so I could not contact you.
所以當變成 passive voice 的時候，simple past tense --> was/were + PP